The present invention relates to a control apparatus of an automatic transmission.
U.S. Pat. No. 4,858,499 (corresponding to Japanese Patent Application Publication No. 63-9771) discloses a previously-proposed control apparatus of automatic transmission. In this technique, a start of inertia phase is determined by detecting the variation of a parameter which starts to vary when the inertia phase starts. This is because the variation of the parameter such as a gear ratio (speed ratio) which varies during the inertia phase needs to be detected in order to reliably judge the start of inertia phase without an error judgment.
However, in the case that it is determined that the inertia phase has started on the basis of the variation of the parameter as mentioned above, the start of inertia phase is determined at a timing delayed from an actual start timing of inertia phase. That is, accurately, a timing when it is determined that the inertia phase has started is not the actual start timing of inertia phase. Hence, U.S. Pat. No. 6,482,126 (corresponding to Japanese Patent Application Publication No. 2001-343068) discloses a technique in which an initial pressure of lockup clutch is learned and controlled based on a slip amount indicated before the inertia phase is started.